It is known in the art to provide a pair of auxiliary side wheels that are to be removably attached to the rear axle of a bicycle to control dynamic lateral instability of the bicycle. Indeed, bicycles are vehicles whose ground stability is dynamically enhanced by increased vehicle speed; at low vehicle speeds, lateral stability is difficult to maintain, particularly for children and other persons unskilled in the art of bicycle handling. These side wheels are most desirable when dealing with children who are learning the rudiments of riding a bicycle and who still have precarious stability when riding their bicycle.
Many auxiliary side wheels that exist have the problem of comprising rigid attachment means for attaching them to a conventional bicycle. Such rigid attachment means are disadvantageous because the unevenness of the ground will often result in one of the side wheels being raised above the ground level exclusively of the laterally opposite other side wheel and therefore not stabilizing the bicycle as it is supposed to; on the other hand, the rear bicycle wheel could be raised above ground level, the rider then temporarily losing propulsion. Furthermore, when the bicycle and its rider enter into a turn, stability of the vehicle will again be compromised, since the bicycle will not be able to incline itself because of the side wheels' rigid attachment.
A few patents have resolved this problem by including suspension means between the bicycle and the auxiliary wheels.
U.S. Pat. No. 5,492,354 issued in 1996 to RAINEY discloses training wheels mounted at the end of a coil spring mounted on each side of the rear bicycle wheel axle. The coil springs have their axes in-line with respect to each other and offset below and parallel to the rear wheel axle. Inasmuch as the coil spring permits upward movement, the training wheels can be pulled backward against the action of the spring. A drawback of the apparatus disclosed by RAINEY is that friction resulting from uneven terrain may cause one wheel to be pulled backwards and thus resist forward movement causing the bicycle to turn. U.S. Pat. No. 2,450,979 issued in 1948 to MOLLER shows a coil spring suspension system for fitting to an auxiliary wheel assembly on a bicycle rear wheel axle. The auxiliary wheel axle is kept downwardly offset from the bicycle gearwheel axle by an L-shaped bracket interconnecting both axles. The hub of the auxiliary wheel is movably interconnected to the bicycle rear axle by an upwardly inwardly inclined, adjustable length coil spring member. Because of the relative angular values between the elongated coil spring member and the two wheel axles, lateral tilt play of the auxiliary wheel axle relative to the bicycle rear axle is limited to a narrow range. The MOLLER device would be expensive to manufacture and prone to become damaged, because of it being made of several separate parts.
U.S. Pat. No. 2,793,877 issued in 1954 to MEIER shows an auxiliary wheel which is mounted near the rear bicycle rear wheel by means of a generally L-shaped flat spring blade. The vertical leg of the L-spring blade and that of a second, rigid L-blade are anchored to the bicycle rear wheel axle. The transverse leg of the rigid blade overlying the transverse wheel axle leg of the flexible blade is movably connected to this flexible blade transverse leg by an adjustable length vertical member. Again, the relative angular play between the auxiliary wheel axle and the bicycle rear wheel axle is quite limited with the MEIER system, notably by the fact that the auxiliary wheel axle motion is limited to a downward motion relative to the horizontal leg of the rigid L-blade (which remains parallel to the bicycle rear wheel axle). The use of a blade spring requires the provision of the second rigid blade and of legs to prevent travel of the blade spring in a horizontal plane either forward or backward.
In both these above noted patents, the auxiliary wheels are functional, but they are complicated in that they necessitate a plurality of parts for installing the side wheels on the bicycle (e.g. brackets or the like, spindles or the like, springs, etc.). It is much more complicated to install the side wheels due to the number of parts involved and it is more probable that a breakage will occur for the same reason. Moreover, the spring adjustment means for the auxiliary wheels provide either upward adjustment or downward adjustment, but not both. Also, neither the MOLLER nor the MEIER reference would seem to enable the bicycle rider to deal effectively with a particular ground surface where the bicycle main rear wheel would engage a groove in the road while both auxiliary wheels would remain at a raised ground level; it would appear that in such a case, the bicycle main rear wheel may lift slightly from the ground, thus compromising ground traction.